Design Considerations and FPGA Implementation of a Wideband All-Digital Transmit Beamformer with 50% Fractional Bandwidth

In this work, we report design and implementation of an all-digital transmit phased array. The key design considerations have been reviewed including applications of multi-core DSM and wideband beamformer based on space-time theory. The built prototype of 8-element array using a commerical FPGA board demonstrated the feasibility of designing real-time wideband digital beamformer. The measured beam pattern for RF frequency of 2.5 GHz with 1.25 GHz bandwidth agreed well with simulation. To the authors' knowledge, this fractional bandwidth of 50% is the widest one reported so far. This advances the state-of-the art in terms of fractional bandwidth by more than 40 times, which shows that all-digital transmitter is a very promising technology for next generation directional communications such as 5G and beyond.